Electric discharge device and method of making



June 26, 1962 H. c. SPICER ETAL 3,

ELECTRIC DISCHARGE DEVICE AND METHOD OF MAKING Original Filed Feb. 16, 1955 2 Sheets-Sheet 1 FlG.l.

INVENTORS: RICHARD F. HAMMOND, HUGH c. spleen,

THEI ATTO" NEY.

H. c. SPICER ETAL 3,041,126

ELECTRIC DISCHARGE DEVICE AND METHOD OF MAKING Original Filed Feb. 16, 1955 June 26, 1962 2 Sheets-Sheet 2 RICHARD F. HAMMOND,

INVENTORSI HUGH C. SPICER,

'77ZZ 0 THEIR ATTO NEY.

United States Patent 3,tl41,126 ELECTRIC DHSCHARGE DEVICE AND METHQD OF MAKING Hugh C. Spicer and Richard F. Hammond, Tell City, Ind, assignors to General Electric Company, a corporation of New York Original application Feb. 16, 1955, Ser. No. 488,462, new Patent No. 2,%3,633, dated Apr. 19, 1961?. Divided and this application May 12, 1959, Ser. No. 817,429

7 Claims. (Cl. 316-9) Our invention relates to electric discharge devices and pertains more particularly to a new and improved high voltage electric discharge device and methods of producing same. This application is a true division of our application, Serial No. 488,462, filed February 16, 1955, entitled Electric Discharge Device, patented April 19, 1960, No. 2,933,633.

During the operation of some high voltage electric discharge devices including glass bulbs, such as high voltage regulator and rectifier tubes used in television receivers, the interior surfaces of the bulbs are bombarded with electrons and are alternately charged and discharged. This sometimes results in the generation of a signal with harmonics extending into the television spectrum and causing radio frequency noise generally known in the art as diodehausen. The diodehausen manifests itself in some television receivers as undesirable black vertical lines at some particular portions of the raster. Additionally, the charging of the bulbs results in glass electrolysis which is also undesirable.

The primary object of our invention is to provide a new and improved high voltage electric discharge device including means for minimizing the effects of bulb charging.

Another object of our invention is to provide a new and improved high voltage tube adapted for use in television receivers and including means for minimizing radio frequency noise in the receivers.

Another object of our invention is to provide a new and improved high voltage electric discharge device including a vitreous envelope and means for minimizing electrolysis in the Walls thereof.

Still another object of our invention is to provide new and improved methods for producing high voltage electric discharge devices adapted for minimizing the undesirable effects of bulb charging.

Further objects and advantages of our invention will become apparent as the following description proceeds and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of our invention we provide an electric discharge device including a vitreous envelope provided with a metallic deposition on the interior surface thereof. The metallic deposition is preferably lead and may be applied by providing in the envelope a material which will vaporize and flash onto a portion of the walls of the envelope with lead when heated to a predetermined degree. Vaporization of the material and flashing of the lead may be effected by depositing the material on an electrode in the device and electrically heating the electrode.

For a better understanding of our invention reference may be had to the accompanying drawing in which:

FIG. 1 is an elevational view of an electric discharge device incorporating our invention and partially broken away to illustrate the manner in which the metallic deposition is provided on the interior surface of the bulb;

FIG. 2 is a somewhat schematic illustration of one manner in which the method of our invention may be practiced;

FIG. 3 is a flow chart illustrating one manner of preparing the electrodes for use in our methods; and

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FIG. 4 is a schematic illustration of automatic means for preparing the electrodes.

Referring to FIG. 1, there is a shown an electric discharge device in the form of a high voltage rectifier tube generally designated 1. The tube 1 includes a glass bulb or envelope 2 in which is housed a cylindrical anode 3 mounted in a suspended manner in the envelope by means of a top cap 4 which extends through and is suitably sealed in the top portion of the envelope.

The anode and top cap are often collectively referred to as an anode assembly. Mounted in the envelope by means of a pair of vertical support rods 5 and disposed in the anode 3 is a filament or cathode 6. Suitably supported beneath the anode 3 and in spaced relation thereto is a shield 7. Suitably secured to the lower end of the envelope 2 is a base 8 carrying a plurality of base pins 9 and a bayonet plug 10' adapted for facilitating insertion of the pins in a tube socket. Leads 11 are electrically connected to the various pins 9 and extend in a sealed manner through the lower end of the envelope for making electrical connections to and supporting the filament support rods 5 and the shield 7 in the envelope.

During normal operation of a high voltage rectifier tube such as that described to this point and not incorporating our invention, the interior surface of the bulb 2 is bombarded by electrons and tends alternately to charge and discharge. This charging and discharging is frequent and abrupt and often results in radiation of energy and generation of a signal with harmonics extending into the television spectrum. As a result, if the tube is used in a television receiver, it causes radio frequency noise generally referred to in the art as diodehausen. Diodehausen sometimes manifests itself in a television receiver as a black vertical line appearing at some particular portion of the raster, such as the left hand edge. Additionally, the referred-to electron bombardment of the glass causes undesirable glass electrolysis.

The bulb charging described above is ordinarily most prevalent or concentrative in the annular area extending between the bottom of the anode 3 and the top of the shield 7 and defined by the spaced dash lines 12 in FIG. 2. In order to minimize the bulb charging and thereby avoid diodehausen in television receivers utilizing tubes such as 1 and to minimize glass electrolysis, we vaporize a material in the tube in the vicinity of the area defined by the lines 12, whereby a thin lead deposition indicated by stippling designated 15 in FIG. 1 is provided on the interior surface of the bulb. The deposition 15 extends over and beyond the area ordinarily bombarded by electrons during tube operation but is not so extensive as to effect a conductive path between the top cap 4 and the leads 11.

The :leaddeposition 15 is effective for distributing the charge or conducting the electrons bombarding the walls of the bulb in this area in such a manner that large charges are prevented from building up or accumulating in any particular spots or areas. This reduces the abovereferred-to energy radiation or signal generation to the extent that when a tube such as that described is employed in a television receiver diodehausen is not encountered. Additionally, due to the reduction of the concentrated charging by the metallic decomposition 15 glass electrolysis is minimized. As a result, in some tube structures where lead glass was formely used because of its relatively high resistance to current how, with our invention a relatively less expensive glass such as lime glass may be employed. In some other tube structures where it is desired to use much higher voltages and where electrolysis effects would be encountered even where lead glass is employed our invention may be advantageously utilized in conjunction with the lead glass.

The lead deposition is preferably applied by substantially uniformly distributing in the rim or rolled lip 16 of the anode 5 a deposit 17 of material which when sufficiently heated will volatilize and flash lead on the interior of the bulb.

As seen in FIG. 2, the heating may be done inductively by an induction coil 18. Additionally, the flashing of the material 17 may be carried out before the tube 1 is tipped-off and while it is being processed on the usual tube processing equipment.

Specifically, the lead may be flashed on the bulb while the tube 1 is held by its exhaust tubulation 19 in an exhaust head 20 of the mentioned usual processing equipment and while the anode 3 is being inductively heated by means of the coil 18 for effecting out-gassing thereof. The flashing of the lead onto the bulb occurs at approximately 800 to 900 C. Thus, it will be seen that by uniformly distributing the material 17 in the anode rim 16 and by taking advantage of the step of heating the anode for out-gassing we accomplish the provision of a lead deposition or coating 15 on the interior surface of the bulb which is substantially uniformly distributed around the tube and covers and extends beyond the area in which bulb charging is most prevalent in an ordinary rectifier tube.

The material l7 which is adapted for vaporizing and flashing the lead deposition 15 on the Wall of the bulb is preferably lead or any suitable compound of lead, such as basic lead carbonate, which will break down to uncombined lead when heated sufficiently under exhaust conditions or when heated sufficiently in avacuurn.

In FIG. 3 is illustrated a method of providing a substantially uniform deposit of basic-lead carbonate in the rim 16 of an anode 3. In this method the anode is dipped with the rimmed edge downward into a receptacle 21 containing a suspension of basic lead carbonate designated 22.

Following dipping of the anode 3 in the suspension 22 in the manner illustrated in *FIG. 3, the anode 3 is set to drain on a drainboard 23 or the like. Thus, the rim 16 is filled with a quantity of the suspension 22. Following draining, the anode is placed in a suitable drying oven 24. in the oven the anode is heated for evaporating the liquid constituent of the suspension in the anode rim. Thus, a substantially uniformly distributed deposit or residue of basic lead carbonate 17 is left in the anode rim. It will be seen that a plurality of anodes may be held in a rack or the like and dipped, drained and dried together to increase production.

After preparation of an anode in the just-described manner it may be mounted or suspended in the bulb by means of a suitable glass-to-metal seal between the bulb and the top cap 4, and the bulb may be sealed to the tube stem including the tubula-tion 19 thereby to arrive at the structure shown in FIG. 2. Thereafter, the tube may be processed in the usual manner and, as described above, during heating of the anode 3 by means of the induction coil 18 for out-gassing of the anode, the basic lead carbonate in the anode rim is caused to break down to lead and this lead is vaporized or flashed onto the interior of the bulb for providing the lead deposition 15'.

In FIG. 4 is illustrated an automatic method of preparing the anodes. In this method the anodes are placed on conveying means generally designated 25 adapted for positioninig each anode first at a reservoir 26 containing a supply of the suspension 22 and then through a suitable oven 27. The oven 27 is similar in construction and purpose to that referred to above and designated 24 in FIG. 3, but is relatively and preferably longer in order to enable complete evaporation of the liquid constituent of the suspension in the anode rim during transit of the anode through the oven.

By means of a tube 23 including a control valve 30 and automatic means generally designated 31. adapted for controlling the operation of the valve 30, the suspension 22 ispoured in predetermined equal amounts into the rims of the anodes as the latter are successively positioned by the conveying means at the reservoir 22. Thus, the rim of each anode is filled with the suspension 22 and, inasmuch as no draining step is necessary, the conveying means 25 is thereafter effective for directly carrying the anode into and through the elongated oven 27 wherein the liquid portion of the suspension is evaporated leaving in the rim a deposit 17 of basic lead carbonate to be flashed. Thereafter the anode is automatically removed from the conveying means and at this stage it is prepared for mounting in the bulb 2 and flashing of the basic lead carbonate for providing the lead deposition 15 in the manner described above with regard to FIG. 2.

While we have shown conveying means including what is illustrated as a conveying belt, the conveying means may take any form. For instance, a chain drive or the like including clamping means or magnetic holding means for holding the anode assemblies by the top caps 4 thereof and thus carrying them to and positioning them at a reservoir such as 26 and through an elongated oven such as 27 may be employed.

The lead suspension utilized in both of the abovedescribed methods of preparing the anodes 3 may be a lead-methanol corrosion product. In an operative arrangement we have found that the product may be prepared by taking a sheet of lead of approximately twelve square feet, rolling it to form a cylinder and immersing it in approximately twenty-eight gallons of commercially available methanol for approximately twenty-four hours. A suspension obtained in this manner is particularly satisfactory in that it requires no agitation to prevent settling and assures substantial uniformity in the amounts of lead carbonate received in the rims of successively processed anodes. It will, of course, be understood that the fore-going is exemplary only and is not intended to be limiting in any manner.

The suspension 22 may also be prepared from powdered basic lead carbonate popularly known as white lead and generally commercially obtainable. First, a stock or paste may be prepared by mixing approximately 450 grams of White lead and approximately 300 cubic centimeters of generally commercially available amyl acetate. This mixture in then milled, as by ball milling, for approximately ninety-two hours to minimize settling during use. The stock or paste obtained in the first described manner is used in proportions of approximately one and one-half cubic centimeters to a gallon of acetone which is also generally commercially available. A suspension obtained in the just-described manner is particularly adaptable for use with the automatic or machine filling method shown in FIG. 4 because of its drying and low odor qualities. Additionally, for most satisfactory results and, specifically, in order to avoid settling and thereby insure substantially uniform amounts of lead carbonate in the rims of successively filled anodes, it is advisable to agitate the suspension obtained by using the powdered basic lead carbonate.

It Will be understood that the suspension 22 may be one of uncombined or metallic lead. Additionally, while the use of the suspension for depositing the basic lead carbonate in the anodes 3 has been found expedient from a manufacturing standpoint, if desired the lead or lead compound may be directly placed or deposited in the mm.

It is to be understood further that while we have shown and described the material to be flashed as deposited in the anode rim, this material could alternatively be held in any desired manner adjacent the region or area to be coated with lead and defined by the lines 12. For instance, the material could be arranged or deposited on a support structure independent of the anode and, if desired, it could be arranged on a separate electrode adapted for being electrically heated by means of an electrical circuit completed through appropriate ones of the pins 11, thereby to raise the temperature of the material to the flashing point.

While We have shown and described specific forms of our invention we do not desire our invention to be limited to the particular forms shown and described, and we intend by the appended claims to cover all modifications within the spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. The method of producing an electric discharge device including an insulative envelope adapted for containing electrode means and means for minimizing concentrative charging of the walls of said envelope consisting in the steps of, locating in said envelope in the vicinity of the area of said concentrative charging a quantity of material selected from the group consisting of lead and basic lead carbonate, and heating said material sufficiently to cited flashing of a lead deposition on said area of concentrative charging for distributing any electrical charges thereon.

2. The method of producing an electric discharge device including a vitreous envelope adapted for containing electrode means and means for minimizing concentrative charging of the walls of said envelope consisting in the steps of, locating in said envelope in the vicinity of the area of concentrative charging a quantity of material selected from the group consisting of lead and basic lead carbonate, and inductively heating said material sufliciently to eifect flashing of a lead deposition on said area of concentrative charging for distributing any electrical charges thereon.

3. The method of producing an electric discharge device including a vitreous envelope, at least one electrode contained in said envelope, and means for minimizing concentrative charging of the walls of said envelope during operation of said device consisting in the steps of, arranging on said electrode adjacent the area of concentrative charging of said envelope a quantity of material selected from the group consisting of lead and basic lead carbonate, and heating said electrode sufficiently to efiect flashing of a lead deposition on said area of said concentrative charging for distributing any electrical charges thereon.

4. The method of producing an electric discharge device including a glass envelope, an electrode including a rimmed edge, and means for minimizing concentrative charging of the area of the walls of said electrode adjacent the rim of said electrode consisting in the steps of, depositing in said rim a quantity of material selected from the group consisting of lead and basic lead carbonate, and electrically heating said electrode sufiiciently to effect flashing of a lead deposition on said area of concentrative charging for distributing any electrical charges thereon.

5. The method of producing an electric discharge device including a glass envelope, an electrode including a rimmed edge, and means for minimizing concentrative charging of the area of the walls of said electrode adjacent the rim of said electrode consisting in the steps of, depositing in said rim a suspension of a material selected from the group consisting of lead and basic lead carbonate, evaporating the liquid constituent of said suspension thereby to leave a substantially uniform residue of said material in said rim of said electrode, and heating said electrode sufficiently to efiect flashing of a lead deposition on said area of concentrative charging for distributing any electrical charges thereon.

6. The method of producing an electric discharge device including a glass envelope, an anode including a rimmed edge, and means for minimizing concentrative charging of the area of the walls of said envelope adjacent said edge of said anode thereby to minimize undesired energy radiation and glass electrolysis consisting in the steps of, dipping said anode in a suspension of material selected from the group consisting of lead and basic lead carbonate, draining said anode, heating said anode to evaporate the liquid constituent of said suspension thereby to leave a substantially uniform residue in said rim of said electrode, mounting said anode in said envelope, and inductively heating said anode sufficiently to effect flashing of a lead deposition on said area of said concentrative charging for distributing any electrical charges thereon, thereby to minimize said undesired energy radiation and glass electrolysis.

7. The method of minimizing charging of the walls of an electron discharge device envelope comprising the steps of arranging on an electrode of said device and adjacent the area of unwanted charging, a quantity of material selected from the group consisting of lead and lead carbonate, and heating said electrode to eifect flashing of a lead deposition on said area of said walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,738,957 Metcalf Dec. 10, 1929 2,462,245 Wooten Feb. 22, 1949 2,556,254 Carne June 12, 1951 2,752,268 Whitfield et a1. June 26, 1956 2,774,686 Hodge Dec. 18, 1956 2,877,143 Gallup Mar. 10, 1959 

